Notes and Reflections on Books and Media
by Hannah Leitheiser
Robert Stawell BALL
So, you read about astronomers grinding their own mirrors by hand, it seems the path length of the light coming into the telescope would have to coincide for constructive interference of the rays -- meaning the lens would have to be accurately ground to smaller than the wavelength of light. Seems unlikely, but maybe. Either that or thinking of the light as a wavefront is somehow wrong.